| 1. |
- He, L, et al.
(författare)
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Glomerulus-specific mRNA transcripts and proteins identified through kidney expressed sequence tag database analysis
- 2007
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Ingår i: Kidney International. - 1523-1755 .- 0085-2538. ; 71:9, s. 889-900
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Tidskriftsartikel (refereegranskat)abstract
- The kidney glomerulus plays a crucial role in blood filtration but the molecular composition and physiology of the glomerulus is not well understood. We previously constructed and large-scale sequenced four mouse glomerular expressed sequence tag (EST) libraries from newborn and adult mouse glomeruli. Here, we compared glomerular EST profiles with whole kidney EST profiles, thereby identifying 497 transcripts corresponding to UniGene clusters that were glomerulus-enriched, that is expressed more abundantly in glomeruli than in whole kidney. These include several known protein-coding glomerulus-specific transcripts critical for glomerulus development and function, but also a large number of gene transcripts, which have not previously been shown to be expressed in the glomerulus, or implicated in glomerular functions. We used in situ hybridization to demonstrate glomerulus-specific RNA expression for six novel glomerular genes and the public Human Protein Atlas to verify glomerular protein expression for another two. The higher mRNA abundance for the eight genes in glomeruli compared with whole kidney was also verified by Taqman quantitative polymerase chain reaction. We surmise that the further characterization of these genes and proteins will increase our understanding of glomerular development and physiology.
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| 2. |
- He, Liqun, et al.
(författare)
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The glomerular transcriptome and a predicted protein-protein interaction network
- 2008
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673 .- 1533-3450. ; 19:2, s. 260-268
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Tidskriftsartikel (refereegranskat)abstract
- To increase our understanding of the molecular composition of the kidney glomerulus, we performed a meta-analysis of available glomerular transcriptional profiles made from mouse and man using five different methodologies. We generated a combined catalogue of glomerulus-enriched genes that emerged from these different sources and then used this to construct a predicted protein-protein interaction network in the glomerulus (GlomNet). The combined glomerulus-enriched gene catalogue provides the most comprehensive picture of the molecular composition of the glomerulus currently available, and GlomNet contributes an integrative systems biology approach to the understanding of glomerular signaling networks that operate during development, function, and disease.
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| 3. |
- Jakobsson, Lars, et al.
(författare)
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Laminin deposition is dispensable for vasculogenesis but regulates blood vessel diameter independent of flow
- 2008
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 22:5, s. 1530-1539
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Tidskriftsartikel (refereegranskat)abstract
- Basement membranes (BMs) consisting of laminins, collagens, and heparan sulfate proteoglycans (HSPGs) are vital for proper endothelial cell function, but many aspects of their role in vascular development remain unknown. Here, we demonstrate that vascular structures within differentiating embryoid bodies are wrapped in a BM composed of alpha 4- and alpha 5-chain laminins, fibronectin, collagen IV, and HSPGs. In sprouting angiogenesis, laminins were produced by stalk cells, as well as the leading tip cell, and deposited along the sprout length, including tip cell filopodia. In embryonic stem cells deficient in laminins, due to lamc1 (laminin gamma 1) deletion, vascular development and organization were largely unaffected. However, the frequency of vessels with wide lumens was increased 4-fold. Laminin-deficient vessels were moreover characterized by increased fibronectin levels and enhanced endothelial cell proliferation. We conclude that laminins are dispensable for vascular development but that they regulate lumen formation in the absence of flow and vascular tone.
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| 4. |
- Liu, Xiao Li, et al.
(författare)
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Characterization of the interactions of the nephrin intracellular domain
- 2005
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 272:1, s. 228-243
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Tidskriftsartikel (refereegranskat)abstract
- Nephrin is a signalling cell-cell adhesion protein of the Ig superfamily and the first identified component of the slit diaphragm that forms the critical and ultimate part of the glomerular ultrafiltration barrier. The extracellular domains of the nephrin molecules form a network of homophilic and heterophilic interactions building the structural scaffold of the slit diaphragm between the podocyte foot processes. The intracellular domain of nephrin is connected indirectly to the actin cytoskeleton, is tyrosine phosphorylated, and mediates signalling from the slit diaphragm into the podocytes. CD2AP, podocin, Fyn kinase, and phosphoinositide 3-kinase are reported intracellular interacting partners of nephrin, although the biological roles of these interactions are unclarified. To characterize the structural properties and protein-protein interactions of the nephrin intracellular domain, we produced a series of recombinant nephrin proteins. These were able to bind all previously identified ligands, although the interaction with CD2AP appeared to be of extremely low stoichiometry. Fyn phosphorylated nephrin proteins efficiently in vitro. This phosphorylation was required for the binding of phosphoinositide 3-kinase, and significantly enhanced binding of Fyn itself. A protein of 190 kDa was found to associate with the immobilized glutathione S-transferase-nephrin. Peptide mass fingerprinting and amino acid sequencing identified this protein as IQGAP1, an effector protein of small GTPases Rac1 and Cdc42 and a putative regulator of cell-cell adherens junctions. IQGAP1 is expressed in podocytes at significant levels, and could be found at the immediate vicinity of the slit diaphragm. However, further studies are needed to confirm the biological significance of this interaction and its occurrence in vivo.
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| 5. |
- Patrakka, Jaakko, et al.
(författare)
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Expression and subcellular distribution of novel glomerulus-associated proteins dendrin, ehd3, sh2d4a, plekhh2, and 2310066E14Rik
- 2007
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Ingår i: Journal of the American Society of Nephrology. - : Ovid Technologies (Wolters Kluwer Health). - 1046-6673 .- 1533-3450. ; 18:3, s. 689-697
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Tidskriftsartikel (refereegranskat)abstract
- The glomerular capillary tuft is a highly specialized microcapillary that is dedicated to function as a sophisticated molecular sieve. The glomerulus filter has a unique molecular composition, and several essential glomerular proteins are expressed in the kidney exclusively by glomerular podocytes. A catalog of > 300 glomerulus-upregulated transcripts that were identified using expressed sequence tag profiling and microarray analysis was published recently. This study characterized the expression profile of five glomerulus-upregulated transcripts/proteins (ehd3, dendrin, sh2d4a, plekhh2, and 2310066E14Rik) in detail. The expression pattern of these novel glomerular transcripts in various mouse tissues was studied using reverse transcriptase-PCR, Northern blotting, and in situ hybridization. For studying the distribution of corresponding proteins, polyclonal antibodies were raised against the gene products, and Western blotting, immunofluorescence, and immunoelectron microscopic analyses were performed. Remarkably, it was discovered that all five transcripts/proteins were expressed in the kidney exclusively by glomerular cells. Ehd3 was expressed only by glomerular endothelial cells. Importantly, ehd3 is the first gene ever shown to be expressed exclusively by glomerular endothelial cells and not by other endothelial cells in the kidney. Dendrin, sh2d4a, plekhh2, and 2310066E14Rik, however, were transcribed solely by podocytes. With the use of polyclonal antibodies, dendrin, sh2d4a, and plekhh2 proteins were localized to the slit diaphragm and the foot process, whereas 2310066E14Rik protein was localized to the podocyte major processes and cell body. This study provides fresh insights into glomerular biology and uncovers new possibilities to explore the role of these novel proteins in the glomerular physiology and pathology.
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| 6. |
- Qian, Hong, et al.
(författare)
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Contribution of {alpha}6-integrins to hematopoietic stem and progenitor cell homing to bone marrow and collaboration with {alpha}4-integrins.
- 2006
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 107:Jan 26, s. 3503-3510
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Tidskriftsartikel (refereegranskat)abstract
- The laminin receptor integrin alpha 6 chain is ubiquitously expressed in human and mouse hematopoietic stem and progenitor cells. We have studied its role for homing of stem and progenitor cells to mouse hematopoietic tissues In vivo. A function-blocking anti-integrin alpha 6 antibody significantly reduced progenitor cell homing to bone marrow (BM) of lethally irradiated mice, with a corresponding retention of progenitors in blood. Remarkably, the anti-integrin alpha 6 antibody profoundly inhibited BM homing of long-term multilineage engrafting stem cells, studied by competitive repopulation assay and analysis of donor-derived lymphocytes and myeloid cells in blood 16 weeks after transplantation. A similar profound inhibition of long-term stem cell homing was obtained by using a function-blocking antibody against alpha 4 integrin, studied in parallel. Furthermore, the anti-integrin alpha 6 and alpha 4 antibodies synergistically inhibited homing of short-term repopulating stem cells. Intravenous injection of anti-integrin alpha 6 antibodies, in contrast to antibodies against alpha 4 integrin, did not mobilize progenitors or enhance cytokine-induced mobilization by G-CSF. Our results provide the first evidence for a distinct functional role of integrin alpha 6 receptor during hematopoietic stem and progenitor cell homing and collaboration of alpha 6 integrin with alpha 4 integrin receptors during homing of short-term stem cells.
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| 7. |
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| 8. |
- Qian, Hong, et al.
(författare)
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Distinct roles of integrins {alpha}6 and {alpha}4 in homing of fetal liver hematopoietic stem and progenitor cells.
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 110:7, s. 2399-2407
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Tidskriftsartikel (refereegranskat)abstract
- Homing of hematopoietic stem cells (HSCs) into the bone marrow (BM) is a prerequisite for establishment of hematopoiesis during development and following transplantation. However, the molecular interactions that control homing of HSCs, in particular, of fetal HSCs, are not well understood. Herein, we studied the role of the alpha 6 and alpha A integrin receptors for homing and engraftment of fetal liver (FL) HSCs and hernatopoietic progenitor cells (HPCs) to adult BM by using integrin alpha 6 gene-deleted mice and functionblocking antibodies. Both integrins were ubiquitously expressed in FL Lin(-)Sca1 (+)Kit(+) (LSK) cells. Deletion of integrin alpha 6 receptor or inhibition by a functionblocking antibody inhibited FL LSK cell adhesion to its extracellular ligands, laminins-411 and -511 in vitro, and significantly reduced homing of HPCs to BM. In contrast, the anti-integrin alpha 6 antibody did not inhibit BM homing of HSCs. In agreement with this, integrin alpha 6 gene-deleted FL HSCs did not display any homing or engraftment defect compared with wildtype littermates. In contrast, inhibition of integrin alpha 4 receptor by a functionblocking antibody virtually abrogated homing of both FL HSCs and HPCs to BM, indicating distinct functions for integrin alpha 6 and alpha 4 receptors during homing of fetal HSCs and HPCs.
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| 9. |
- Sun, Ying, et al.
(författare)
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Glomerular Transcriptome Changes Associated with Lipopolysaccharide-Induced Proteinuria
- 2009
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Ingår i: American Journal of Nephrology. - : S. Karger AG. - 0250-8095 .- 1421-9670. ; 29:6, s. 558-570
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Tidskriftsartikel (refereegranskat)abstract
- Background: Global gene expression patterns have recently been characterized in normal glomeruli, but gene expression changes that accompany glomerular disease remain poorly characterized. Method: Here, we mapped global glomerular gene expression profile changes occurring in conjunction with lipopolysaccharide (LPS)-induced proteinuria in mice. Results: We observed dramatic transcriptional reprogramming in glomeruli in response to LPS, representing some 20% of all genes and about 45% of the genes that are normally highly expressed in glomeruli. Bioinformatic analysis revealed significant changes in transcripts encoding proteins involved in the regulation of adherence junctions, actin cytoskeleton and survival in podocytes. In the LPS-treated mice, we observed dysregulation of genes expressed in glomerular endothelial and mesangial cells and in podocytes, there was also a significant decrease in podocyte number. Moreover, collagen alpha 1, alpha 2 (IV) and laminin 10 (laminin alpha 5 beta 1 gamma 1), which are expressed in immature glomeruli, were upregulated in the glomeruli of LPS-treated mice, suggesting remodeling of the glomerular basement membrane and activation of mesangial cells. By superimposing the LPS-induced changes onto GlomNet, a protein-protein interaction network was predicted for podocyte proteins affected by LPS. Conclusions: The detected changes in glomerular gene expression and their involvement in protein interaction networks provide putative markers for early and transient glomerular injury and proteinuria. Copyright (c) 2009 S. Karger AG, Basel
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| 10. |
- Takemoto, Minoru, et al.
(författare)
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Large-scale identification of genes implicated in kidney glomerulus development and function.
- 2006
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Ingår i: The EMBO journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 25:5, s. 1160-74
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Tidskriftsartikel (refereegranskat)abstract
- To advance our understanding of development, function and diseases in the kidney glomerulus, we have established and large-scale sequenced cDNA libraries from mouse glomeruli at different stages of development, resulting in a catalogue of 6053 different genes. The glomerular cDNA clones were arrayed and hybridized against a series of labeled targets from isolated glomeruli, non-glomerular kidney tissue, FACS-sorted podocytes and brain capillaries, which identified over 300 glomerular cell-enriched transcripts, some of which were further sublocalized to podocytes, mesangial cells and juxtaglomerular cells by in situ hybridization. For the earliest podocyte marker identified, Foxc2, knockout mice were used to analyze the role of this protein during glomerular development. We show that Foxc2 controls the expression of a distinct set of podocyte genes involved in podocyte differentiation and glomerular basement membrane maturation. The primary podocyte defects also cause abnormal differentiation and organization of the glomerular vascular cells. We surmise that studies on the other novel glomerulus-enriched transcripts identified in this study will provide new insight into glomerular development and pathomechanisms of disease.
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